System for television and sound



July 28, 1936. J. v. L. HOGAN SYSTEM FOR TELEVISION AND SOUND 2Sheets-Sheet 1 Filed May 29, 1950 AMPl/F/Ek 25 Rwy/17m? July 28, 1936.J. v. HOGAN SYSTEM FOR TELEVISION AND SOUND Filed May 29, 1930 2Sheets-Sheet 2 Patented July 28, 1936 PATENT OFFICE I SYSTEM FORTELEVISION AND SOUND John V. L. Hogan, Forest Hills, N. Y., assignor toRadio Inventions, Inc., New York, N. Y., a. corporation of New YorkApplication May 29, 1930, Serial No. 457,217

'1 Claim.

This invention relates to systems for transmitting to a distancesynchronized moving images and sound, by such means as motion picturefilm provided with recorded sound carried upon the same film or upon aseparate record or records. aural records are now provided with a soundtrack situated at one side of the image and bearing a constantspatial-temporal relationship to the image record, this relationshipbeing such that apparatus for recording or reproducing the sound and theimage can operate simultaneously upon different portions of the film,and yet produce proper ultimate synchronization of the two effects.

This invention has for one of its objects a provision of means forproducing by the employment of film such operations as are necessary fortransmission of the image and the sound record to a distance.

Another object is to combine such transmission with the transmission ofuniform synchronizing signals over a common channel of communlcation.

' Another purpose isto provide apparatus which can be readily changed soas to operate with either sound or silent films, by simple and rapidmechanical adjustments.

A further object is to allow picture filmnot carrying a sound track tobe scanned and kept in synchronization with an external sound record,such as one of the usual disc type.

Another object is to allow continuous motion of the film throughout thetransmitting apparatus, instead of the intermittent motion heretoforeemployed in projecting motion picture film.

My invention includes picture transmission and sound pick-up devices aswell as synchronizing means applying to both the synchronizing of sightand sound and to the synchronizing of transmitter and receiver. Thissynchronization may be facilitated by operation of both transmitter andreceiver from a common power line. In a preferred form illustrated inthe accompanying drawings:

Fig. 1 is a standard motion picture film with Such films as carry bothvisual and by a transmitter scanning the-image of Fig. 1 on the lineM-N.

Fig. 4 shows a. "silent filrn i. e., a film having no sound track usedin this system.

Fig. 5 shows a wave form corresponding to 5 the use of silent filmas inFig. 4.

Fig. 6 illustrates a combined picture and sound pick-up assembly.

Fig. 7 shows a transmitter utilizing a silent" film synchronized with a,disc sound record.

Figs. 8, 9, 10 show details of methods of automatically starting a filmand sound record in' synchronization.

One principle of my invention is illustrated by the drawings, Figs. 1and 2, where l is a standard sound film, with sound track 2, and guidesections 3 perforated at t. A picture is diagrammatically shown by 5.

Below this film (and shown spaced therefrom for purposes of clearerillustration) is a section of the edge of a scanning disc ill. The filmI is in continuous downward motion, as indicated by the arrow; past theslit It in plate It which may be adjustable as to width but is in fixedposition, and scanning disc ill is in rotation, as likewise indicated bythe arrow thereupon. Disc l 0 is provided with radial slits I Ipreferably narrower than slit l4 and cooperating with it to scan theimage on the moving film.

At 20 in Fig. 2 is diagrammatically shown a light source, casting a lineof light upon a film image to be scanned, and at 2! a photo electriccell actuated by the scanning beam after passage through the film andscanner mechanism.

The lines 22 represent the rays bounding the 3 beam of light utilizedduring the scanning process.

Wires 23 convey the electrical output'oi. the device to the usualamplifiers and wires 24 furnish energy to actuate light source 20.

The width of image scanned by this mechanismis delimited by movablescreening pieces it, supported on fixed members 55 and adjustable inrelation to one another and to the film by the cooperation of slots ISin the movable screens,- and fastening devices i3 in the fixed membersI5. Any equivalent mechanical construction allowing adjustment of thesescreens can be employed. If desired, the film may be located 'to pass ata point remote from the scanning slot and disc,

and the picture images projected optically upon the scanning system.

The relation of the distance between adjacent slits of the scanningdisc, width of the aperture betweenthe screens, and the width of variousportions of the film is of importance in the operation of my inventionand to more. clearly bring out its relationship I have indicated someimportant distances by letters and dotted lines in Figs. 1 and 4.

Referring to Fig. lAB is the width of the left hand guide section.

.BC is the width of the sound track. CD is the width of the image track.

DE is the width of the righthand guide section. EF is a distance equalto BC, but not an actual physical measurement appearing on the film.

As shown by prolongation of these lines, the active scanning distance isdelimited by the screens l2 to coincide with the portion CDof the film.Thus the photo-electric response is limited by the width of thevisualimage track.

The distance between two successive slits of the scanning disc, asindicated by dimension lines marked A'D is made equal or, where aprojection system is employed, proportional, to the distance'AD upon thefilm.

As the scanning disc rotates it is evident that there will be a time,interval when no slit is scanning the image. This interval is spatiallyrepresented by A'D"CD. Since A'D=AD, this differential interval equalsAC. Since vAl3=Dl52 by the usual construction of motion picture film,

- another.

and since EF was selected-to equal BC, therefore adding equals, weobtain AC=DF. This means that the intervals of non-excitation of thelightresponsive device-2| will be uniform, both in regard to theirduration and their spacing from one In Fig. 1A' bothscreens are shownunited into a single structure to facilitate adjustments.

In Fig. 3 is shown and approximate representation or the current curvedue to'an ideal photo electric cell when responding to the scanning ofthe image of Fig. 1, for one row of horizontal elements corresponding tothe line indicated by MN. This curve does not show the current asdelivered by the cell, but an exact inversion of the same.

It is well known that when employing the usual ter while on thetransmission channel, so-that greater light intensity gives greatercurrent, or

greater high frequency energy, if carrier currents are employed.

In the receive! these signals may be mverted it may be synchronized witha disc, upon which during amplification, but are usually delivered tothe final translating device in the direct form. With my'invention, theinversion described at the transmitter, allows the inverted signal topass over the transmission channel, and at the receiver to bere-inverted before final delivery to the translating device. 7

While not confining myself to the transmission of such an invertedsignal, to be corrected. by

reinversion at the receiving station, I consider this invertedtransmission preferable for some purposes and as a part of my invention,constituting an improvement over the prior art.

The intervals AC and DF as continuously repeated, constitute uniform andrhythmicalimpulses, positive in nature for the inverted signal shown,and negative for a non-inverted signal. These impulses can, by virtue oftheir distinctive The current character, be employed at the receivingmecha- .ing plates are both shiited preferably so that one half of thewidth corresponding to the former sound track will be masked on eachside.

This leaves the ratio of picture signal to synchronizing impulses thesame as before since AD equals AD of Figs. 1 and 3. Thus no readjustmentof the receiver is required because of change from one type offilm tothe other at the transmitter. The loss of this small amount of the imagespace is of little importance compared with the maintenance ofuniformity of transmitted impulses for the synchronizing system hereemployed.

Fig. 5 shows plainly that the synchronizing im- .pulses remainunchanged. This is also evident from the fact that the slit spacing onthe disc and the aperture width between the screens are both unchangedfrom their values as illustrated in Fig. 1, for sound film. I

In Fig. 6 is illustrated diagrammatically the pick up for both image andsound operating upon a' continuously moving film l, carrying bothrecords, which is moved by sprockets 29 from reel 32 onto reel 33, beingoptically scanned at the point 3| and having the point 30 located(either ahead or behind the image-scanning point) at the proper distancefrom said point 3!, to accord with the temporal-spatial relationship ofthe recording of image and sound upon the film. Motor 28 drives scanningdisc l0, and light source 20 and light cell 23 cooperate therewith toscan in the usual fashion. At point 30, light from a source 34-fedenergy by'wires 21-with suitable optical system, not shown,'passesthrough the sound track and is analyzed into an electrical signal by thelight sensitive cell 35 with wires 26 for output. The output of this'cell is magnified by suitable amplifiers and passed to a communicationchannel. The optical pick-up system may be similar tothat of Fig. 1.

Distance 30-3! can be varied to secure proper synchronizatiombymovingeither of these points withre'spect to the other, 30 being in generalthe simpler to move.

In case that a non-sound bearing film is used,

appropriate sound has been recorded, in the manalready operating atsynchronous speed, may not be caused to leave this speed when theelectrically governed clutch 43 controlling the operation of theturntable 48, the latter preferably of light weight, is operated uponthe starting of the film moving mechanism 29, 49, 50, 5| by the meanshereinafter indicated. 46 is a suitable device abstracting power fromthe power mains and delivering it to clutch 43, when contact device 44is operated. 52 is a sound pick-up, 53 a transmission circuit toamplifier 64 whose output is delivered through conductors 55 to thechannel for sound transmssion. Scanning disc, light source,photoelectric cells, etc., are numbered as in Figs. 1 and 2, and may beidentical with those elements in that figure.

Drive sprocket 29 upon shaft receives power through clutch member 49,upon the same shaft which latter in turn is actuated by clutch'member50. This last member is driven by key 89 from shaft 5| upon which it canslide to engage member 49. Shaft ii is indirectly driven from motor 40,and therefore is in synchronism with the scanner disc. Suitable speedreduction gears 10, chain II, sprocket wheel 12, and shafts 13 and 14,may be employed for this purpose. The slots 56 in member 49, determinethe functioning of the clutch at certain points only. This assures theproper relationship of the scanner disc and the film movement, andlikewise assures that the receiver, kept in synchronism by the device ofFig.

1, or at otherwise, will receive the inauguration of the transmission ofa new film, without readjustment, provided it was properly adjusted fora prior film transmission, Figure 8 represents a portion of one devicefor securing simultaneous starting of sound record 48 and the film. Uponrecord 58 are shown blank groove A and sound bearing groove D, joiningat point C. If there were no lag or inertia to the entire startingmechanism the needle of the sound pick-up would rest at this point. Dueto the inevitable presence of some inertia it may be desirable to startthe record slightly before the sound track itself is reached. Brepresents such a prior point of needle rest.

Likewise some yielding device such as a damped spring member, not shown,may be employed beby hand or otherwise.

tween the clutch and turntable, to lessen the shock of startingsuddenly. This member should be so constructed as to yield only atstarting, and thereafter, during operation, to return automatically toan unfiexed position.

Fig. 9 shows one method of giving the auto matic starting impulse.Starting point E upon the film is indicated in the usual manner.

A depression 6! in the edge of the film, at a suitable interval frompoint E, allows a light contact actuating member 58 to function, assaid'depression passes this member, thereby closing momentarily contacts59, controlling the release of the record clutch through wires 66 andthe control mechanism id-66-63 of Fig. 7.

Fig. indicates another method of deriving the starting impulse, wherethe contact actuating member 58 momentarily falls into a depression 6!in a disc 51, mounted on the shaft 5|, bearing driving sprocket 29.

In order to start transmission with any of these devices, the film andsound disc are set to the starting marks. The motors 90 and M of Fig. 7are running. Clutch device 69-50 is open and hence the film stationary.When ready to inaug'urate transmission, this clutch may be closed 29 andconsequent movement of film I, the contact making devices of'Figs. 9 or10 function at the proper time. The electrical impulse derived therefromcooperates with signal power box 46 and electrically operated clutch 43,to engage the Upon rotation of sprocket latter, thus startingsynchronous transmission, as explained in the connection with Fig. 8.

- My invention has many advantages which are apparent from the foregoingdescription, of which some are here mentioned. The use of mo- 5 tionpicture fllm in, continuous motion at both the image and the soundpick-up points greatly simplifies the operation of the transmittersystem. No complicated means for exposure of asingle image heldstationary for a fixed interval 10 while being scanned is needed. Alsono loop of film between the two pick-up points is needed, thus promotingmore accurate synchronization of image and sound. Another advantageconse- I quent from the use of film continuously moved is that lesspower is required for its movement, than when it is stopped and startedmany times'per second, as in the usual mode of operation.

This allows smaller driving motors to be used than with intermittentmotion, for equivalent 2i)v constancy of speed, or vice versa.

Likewise the wear and tear on the film, especially around the sprocketholes, will be lessened.

Operation will be more nearly silent. Economy of apparatus andmaintenance thereof will result. 25.

Another advantageous result of continuous motion of film, is that theidle time intervals ordinarily caused by the movement of film, betweenpictures, will be greatly reduced, and with pictures spaced properlyupon the film, may be made 80 to almost reach zero. This means a greateraverage illumination at the receiver, amongst other advantages.

The presence of a time lag between throwing the load upon film drivemotor and sound disc drive motor, respectively, distributes the suddenload upon the power line in a fashion less likely to cause disturbancesthereof.

The employment of a single channel for the transmission of image andsynchronizing impulses results in simplicity of apparatus, conservationof channels, especially important for radio transmission, and economydue to saving of apparatus, lines, power, etc.

The slight adjustment of the screening members, necessary to change fromsound to silent film is easily made, and may be performed simultaneouslyupon both members by simple-mechanical means, such as making the members|2l2 integral as a diaphragm plate having a rectangular aperture ofwidth C-D Fig. 1. .The inversion of signals, giving a positive characterto the synchronizing signals, as well as to shaded portions of theimage, makes use of the power available to keep a higher average level,and promotes easier reception, especially with a radio link of varyingattenuation present in the transmission channel.

lifhe arrangement of Fig. 7 allows either special or the usual startingmarks of records and films to be employed in order to assure immediatesynchronism, upon starting. Also special starting systems other thanthose of Fig. 8 can be used. A dark or light sectionin the film canactuate a. special light sensitive cell, for example, which can actuatethe record clutch through a. suitable amplifier and relay system, theessential being to start the film-in proper phase relation to the linealternations and hence all receivers synchronized therefrom, and tostart the sound synchronously with the film.

Many variations in the details of the apparatus hereindescribed asillustrative of my invention are possible without departing from thescope of the same, as set forth in the appended claim.

The light'source and lightsensitive cell may have their relativepositions reversed instead of allowing the illumination of only oneelement or the film at one moment. The method shown, however, may be ofadvantage if the light is accompanied by a'considerable amount ofradiant heat. Whichever arrangement of these two units is employed, itis possible, and maybe preferable,

to confine the illuminating beam to cover merely mechanical ormechano-electrical movements designed to rapidly and expeditiouslysecure such rearrangements, reconnections and-readjustments of themechanical and electrical units, and of themutual cooperation of thesame, as may be needed to readily change the transmission from that ofsilent to that of sound film (either recorded on the film or externally)or vice versa, as the case may be.

To aid in securing synchronism it is often desirable, when possible, tooperate or controLthe scanning elements at bothtransmitter .re-

ceiver from a common source of power, for exam- I pie by usingsynchronous motors driven troma common power network carryingalternating current of a'uniiorm frequency. V In case thatit is desiredto operate the device with a separatesound record ot made in synchronismwith the film, it-is possible to employ the adjustable speed coordinatorshown in my co-pending application, Ser. No. 455,677, for Moving Pi tureandsound control for the securing of this result. I v

'Other modifications in the mechanisms and processes may be made withinmy invention the, scope of which is defined in the claim;

I claim:

A. television transmitting system operating upon motion picture filmbearing a series of discrete images to be transmitted, including meansfor scanning said film transversely of its length 29 and at a relativelyhigh speed, discrete and independent means for moving said filmin thedirection of its length so as to cause it to be scanned ata relativelylow speed in a direction perpendicular to "said first-mentionedscanning, and unitary coupling means whereby said meansior moving saidfilm may be made operative only at a predetermined point of phase inrelation to the position or the boundaries separating said series ofdiscrete images and are prevented from becoming operative at all otherpoints of phase relationship.

JOHN V. L; HQGAN.

